The present invention relates to catheters for measuring urethral pressure, along the length of the urethra, which is provided at a distance from the closed distal extremity with a lateral outlet for a fluid fed in at a constant rate of flow through a passage arranged for connection to a measuring instrument.
To be able to reach a diagnosis in the case where urinary incontinence occurs, use is made of urethrometers for measuring the urethral pressure gradient, which utilise a catheter which has one or two circular lateral wall perforations in the area of the distal end. A fluid is fed to the wall perforation or perforations at a constant rate of flow by a pump, through the catheter connected at the proximal end to a pressure gauge, said fluid undergoing a pressure rise and exerting said pressure through the wall perforation on the surface of the urethra surrounding the catheter, until this back-up pressure becomes a little higher than the back pressure of the urethra and fluid consequently issues from the catheter through the perforations. This back-up pressure is recorded as a graph by the measuring instrument at mensuration points along the length of the urethra, whilst the catheter is drawn out of the urethra at as uniform a speed as possible.
It has been observed that no precise measurement of actual back or back-up pressure against the urethra is possible with a catheter of the kind hereinabove referred to, since the back pressure is measured practically only in punctiform manner along the length of the urethra and since no unequivocal co-ordination is possible between the momentary pressure value and the point of measurement.
It is therefore an object of the invention to provide a catheter for securing precise measurements of the actual back pressure against the urethra.